JP4885937B2 - Fuel injector assembly - Google Patents

Abstract

A fuel injector assembly (10) comprising an injector body (12) having a leading end (16), a fuel inlet passage (30), a backleak passage (22) and a trailing end (20) which terminates in an end surface (26); a cap (14) that fits over the trailing end (20) of the injector body (12) to define therebetween a chamber (60) for receiving fuel from said backleak passage (22); and a seal (42) for sealing said chamber (60) to prevent the flow of fuel therefrom, wherein said seal (42) is disposed between said end surface (26) of the trailing end (20) and an inlet end (32) of said fuel inlet passage (30).

Description

  The present invention relates to a fuel injector assembly and an engine having such a fuel injector assembly.

  The conventional fuel injector is provided with a connecting portion extending in the axial direction provided with a thread at the rear end in order to be attached to the high-pressure fuel delivery pipe. The minimum bend radius allowed for this piping creates problems for installation and limits the height of the assembly.

  It is known to provide a fuel injector having an injector body with an inlet protruding from a side for connection to a high pressure fuel delivery line. This arrangement eliminates or at least reduces height problems. However, such a side approach fuel injector provided with an inlet portion on the side causes a problem when the engine top cover is installed on the installed injector. Specifically, such a cover is provided with a hole that allows the cover to be placed over the fuel injector, and a hole seal is attached to the hole. When such a cover is attached to the installed side approach fuel injector, the hole seal is damaged or destroyed. If the inlet portion arranged on the side is not perpendicular to the injector body, this problem can be eliminated by removing the seal before installing the engine cover and then installing and adjusting the seal. However, in this case, the required installation work increases. Also, when the angle of the side entrance is steep with respect to the injector body in order to facilitate installation of the engine cover, the height obtained by providing the entrance on the side is reduced. The benefits are reduced.

According to a first aspect of the invention, in a fuel injector assembly,
An injector body having a front end, a fuel inlet passage, a back leak passage, and a rear end terminating at an end face;
A cap attached to the rear end of the injector body, and a chamber for receiving fuel from the back leak passage is formed between the cap and the rear end by attaching the cap to the rear end of the injector body. And
In addition, the fuel injector assembly
In order to prevent fuel from flowing out of the chamber, there is provided a fuel injector assembly, comprising a seal for sealing the chamber, wherein the seal is disposed between the end face of the rear end and the inlet end of the fuel inlet passage. Provided.

Thus, the present invention provides a fuel injector assembly having a back leak chamber that is simple in construction.
Preferably, the seal includes an O-ring. Conveniently, the cap includes a substantially cylindrical body having a groove formed in the inner surface for seating an O-ring. In another aspect, or in addition, the injector body includes a groove for seating an O-ring.

Preferably, the inlet end of the fuel inlet passage is formed in the side wall of the injector body, and the cap includes an opening through which fuel passes during use and is supplied to the fuel inlet passage.
Preferably, an inlet connector having a fuel delivery passage is included, the inlet connector can be secured to the cap so as to extend through the opening, and fuel can pass from the fuel delivery passage into the fuel inlet passage.

Preferably, the cap includes an outlet that is connectable to the back leak return line and is in flow communication with the chamber.
In another aspect, an internal combustion engine equipped with a fuel injector assembly according to the first aspect of the present invention is provided. More preferably, the engine is provided with a cover, and the rear end of the injector body and the cap are disposed outside the cover.

  Embodiments of the present invention will now be described by way of example only with reference to the accompanying drawings.

FIG. 1 is a partial cross-sectional view of a fuel injector installed on a top cover of an engine, viewed in the direction of arrow I in FIG. FIG. 2 is a plan view of the fuel injector as viewed from above in FIG. FIG. 3 is a partial cross-sectional view of the fuel injector installed on the top cover of the engine, viewed in the direction of arrow I in FIG. FIG. 4 is a plan view of the fuel injector as viewed from above in FIG. 3.

  Referring to FIGS. 1 and 2, the fuel injector 10 includes an injector main body 12 and components (for example, joints) in the form of a cap 14 attached to the injector main body. The injector body 12 is essentially a normal or mere cylindrical body, and has a front end 16 to which a nozzle designated by reference numeral 18 is attached and a rear end 20 to which a cap 14 is attached. The injector body front end 16 and nozzle components may be of any suitable known type and include features that assist in mounting and sealing the engine port.

  The injector body 12 is provided with a back leak passage 22. The back leak passage 22 extends from an inlet end (not shown) to an outlet end 24 disposed on the lateral end surface 26 of the injector body. The injector body 12 is further provided with a fuel inlet passage 30. The fuel inlet passage 30 extends in the length direction of the injector body in parallel with the axis 34 of the injector body. This fuel inlet passage 30 serves to deliver high pressure fuel to the front end 16 of the injector body for supply to the engine via the nozzle 18. The fuel inlet passage 30 has an inlet end 32 formed by a transverse perforation. The transverse piercing portion extends perpendicular to the axis 34 of the injector body 12 through the side of the injector body. The inlet end 32 of the fuel inlet passage includes a conical sealing surface for mating with the inlet connector 36.

  The cap 14 is a metal part having a substantially cylindrical body 38. One end of the cylindrical main body 38 is closed by a lateral wall 40, and is sized to fit over the rear end 20 of the injector main body 12 with a gap. A groove in which an O-ring 42 for sealing the injector body 12 is seated is provided inside the cylindrical body 38. However, instead, the injector body 12 may be provided with a groove in which the O-ring 42 for sealing against the inside of the cylindrical body 38 is seated. In another aspect, corresponding grooves may be formed in both the cylindrical body 38 and the injector body 12.

  The cap 14 is provided with a substantially tubular (substantially tubular) extension 44. The extension is integrally formed with the cylindrical body 38 and projects from the body in a direction substantially perpendicular to the axis of the body 38. The tubular extension 44 forms an opening in the cap 14, through which fuel is supplied to the inlet end 32 of the fuel inlet passage 30.

  The inlet connector 36 is a substantially cylindrical body provided with a fuel delivery passage 46 extending in the axial direction. The fuel delivery passage is formed by a series of perforated holes. These perforated holes include holes sized to receive the edge filter 48. A perforated hole at the upstream end of the fuel delivery passage 46 provides a conical surface 50 for sealing engagement with a suitably shaped end of a high pressure fuel delivery line (not shown). The inlet connector 36 includes a male screw (outer screw) 49 at the same end. This male thread allows the high pressure fuel delivery line to be connected to the inlet connector 36 using a union nut.

  A conical surface 52 is provided at the front end of the inlet connector 36 to reach a male screw portion (outer screw portion) 54. The male screw portion 54 engages with a female screw (inner screw) 55 provided at the inner end of the tubular extension 44 of the cap 14. A hexagonal forming portion 56 is provided on the inlet connector 36, and the inlet connector 36 can be firmly fixed to the cap 14 by screwing the male screw portion 54 into the female screw 55 of the tubular extension 44. The conical surface 52 has a shape that is complementary to the conical sealing surface of the inlet end 32 of the fuel inlet passage 30 so that when the inlet connector 36 is screwed into place within the tubular extension 44, the conical surface 52 The two surfaces engage to form a seal between the inlet connector 36 and the injector body 12. The engagement between the two conical surfaces further secures the cap 14 to the injector body 12. This substantially prevents or prevents relative movement between the two parts 12,14.

  When the cap 14 is fixed at a predetermined position of the free end 20 of the injector body 12, the lateral wall 40 is disposed so as to face the lateral end wall 26 of the injector body 12 and spaced from the lateral wall 40. A back leak vent chamber 60 for receiving fuel from is formed therebetween. The cap 14 is provided with an outlet connecting portion 62 for connecting to a back leak return pipe (not shown). In this embodiment, the outlet connecting portion 62 is a push-fit type connector that can be sealed and engaged with the back leak return pipe by a push-fit, but a connector of another mode (for example, a screw-mounted connector) may be used. . The outlet connection 62 is in fluid communication with the back leak vent chamber 60. As a result, the back leak fuel from the chamber 60 can be introduced into the back leak return pipe and returned to the low pressure fuel reservoir.

  In use, the injector assembly 10 is first installed in the engine (not shown) by first fitting the front end 16 of the injector body 12 (without the cap 14 and the inlet connector 36) into the inlet port of the cylinder head of the engine. Installing. Next, the engine top cover 70 is disposed on the injector body 12 so as to be covered from above, and is attached to a cover sheet provided in the engine. At this time, the rear end 20 of the injector body protrudes through a hole provided in the top cover of the engine (in fact, the multi-cylinder engine has a plurality of injector bodies attached to the respective inlet ports, The engine top cover has holes for each of these injectors). The engine top cover 70 is provided with a sealing element 72 that is in sealing engagement with the injector body 12 around the hole.

  After fixing the engine top cover 70 in a predetermined position, the cap 14 is fitted to the rear end 20 of the injector body 12, and the O-ring 42 provided on the cylindrical portion 38 of the cap 14 is engaged with the injector body 12. Let Prior to installation of such a cap 14, the tubular extension 44 is preferably at least roughly aligned with the inlet end 32 of the fuel inlet passage 30. The inlet connector 36 is then inserted into the tubular extension 44 of the cap 14 and rotated to engage the thread 54 with the female thread 55 of the tubular extension. When the conical surface 52 of the inlet connector 36 began to engage the conical sealing surface of the inlet end 32 of the fuel inlet passage 30, any misalignment was automatically corrected and applied to the hexagonal formation 56. The wrench allows the inlet connector 36 to be screwed firmly in place. If the tubular extension 44 is not well aligned with the inlet end 32 of the fuel passage 30 when screwing the front end of the inlet connector 36, the conical surface 52 is engaged with the conical sealing surface of the inlet end 32. The cap 14 can be rotated relative to the injector body 12 until it is felt. When the inlet connector 36 is screwed firmly into place, the relative movement between the cap 14 and the injector body 12 is substantially prevented and the back leak vent chamber 60 leaks between the cap 14 and the injector body 12. It is sealed by O-ring 42 so as not to cause

  In order to complete the mounting process, the end of the high pressure fuel delivery pipe (not shown) is pushed into the conical surface 50 and the union nut is screwed onto the thread 49 so that the high pressure fuel delivery pipe (not shown) is , Fixed to the inlet connector 36. Further, a back leak pipe (not shown) is fitted to the outlet connecting portion 62 by press fitting.

  It will be appreciated that the above-described embodiment provides a side approach fuel injector 10 that can be easily installed in an engine having an engine top cover 70. The injector body 12 can be installed separately from the cap 14 and the inlet connector 36, and is simply a cylindrical body as a whole. Therefore, the engine top cover 70 and the engine top cover hole seal 72 are damaged to the installed injector body 12. It can be installed relatively easily without the danger of damage. After the engine top cover 70 is installed, the cap 14 and the inlet connector 36 can be easily attached to the injector body 12. Thus, the advantage of reducing the available height when using a side-injection fuel injector can be easily obtained even when the engine top cover is installed on the fuel injector.

  It will further be appreciated that the above-described embodiments provide an injector assembly having a back leak chamber that can be sealed by a single O-ring. Thus, manufacturing costs, assembly time, and associated assembly costs are minimized.

  As described above, the O-ring 42 is preferably held in a groove formed in the inner surface of the cylindrical body 38 of the cap 14. Thus, during assembly, the O-ring 42 is placed in the groove and the cap 14 is pressed against the rear end 20 of the injector body 12. When the groove is formed on the outer surface of the injector body 12, the O-ring 42 is first pushed onto the rear end 20 of the injector body 12 in order to place the O-ring 42 in the groove, and then the cap 14 Is inserted into a predetermined position on the rear end 20 of the injector body 12. For both of the above-described configurations, during assembly, the O-ring 42 is positioned between the end face 26 of the injector body 12 and the inlet end 32 of the fuel inlet passage 30 so that the O-ring 42 is in contact with the fuel inlet passage 30. There is no risk of damage by the edge of the transverse perforation at the inlet end 32 of the. Such damage occurs when the O-ring 42 is positioned along the injector body 12 near the nozzle 18 and opposite the inlet end 32 of the fuel inlet passage 30.

  Another advantage of the embodiment described above is that the O-ring 42 is connected to the end face 26 of the injector body 12. By disposing it between the inlet end 32 of the fuel inlet passage 30, the high-pressure fuel connection between the inlet connector 36 and the injector body 12 is disposed outside the back leak chamber 60. Thus, if the inlet connector 36 does not properly mesh with the conical surface of the inlet end 32 of the fuel inlet passage 30, fuel leakage will occur outside the injector body 12, either during assembly or during use after assembly. It looks in. For example, fuel leaks from the open end of the cylindrical body 38 of the cap 14. This is convenient because it clearly indicates that the injector assembly 10 is faulty. On the contrary, when the inlet connector 36 is disposed in the back leak chamber 60, the leaked fuel flows into the back leak chamber 60 and flows into the low pressure fuel reservoir through the back leak return pipe. This means that a failure is missed. Thus, the injector assembly of the embodiment described above increases the chance of diagnosing a failure in the event of a failure.

  It will be understood that the back leak vent chamber 60 need not be provided between the lateral end wall 26 of the injector body 12 and the lateral wall 40 of the cap 14. Instead, an appropriately positioned recess may be provided in the joint so that a back leak vent chamber is formed between the joint and the side wall of the injector body 12.

  It will be appreciated that the location of the cap 14 outlet connections or fittings can be selected according to the particular engine in which they are installed so as to provide an optimal back leak return routine. One alternative position for the outlet connection is shown in broken lines in FIG. In another aspect, the cap 14 may be provided with two outlet connections 62 to facilitate series connection of the back leak chambers of each of the plurality of injectors of the engine.

FIG. 3 shows another form of engine top cover hole seal 72.
FIG. 4 shows another position of the outlet connector 62.
The cap 14 or the joint is formed of a suitable metal such as steel. However, it may be formed of non-metallic materials such as ceramics having necessary characteristics and appropriate engineering plastics.

DESCRIPTION OF SYMBOLS 10 Fuel injector 12 Injector main body 14 Cap 16 Front end 18 Nozzle 20 Rear end 22 Back leak passage 24 Outlet end 26 Horizontal end surface 30 Fuel inlet passage 32 Inlet end 34 Axis 36 Inlet connector 38 Main body 40 Side wall 42 O-ring 44 Extension 46 Fuel Outlet passage 48 Edge filter 49 Male thread (external thread)
50 Conical surface 52 Conical surface 54 Male thread (outer thread)
55 Female thread (inner thread)
56 Hexagon forming part

Claims (9)

A fuel injector assembly (10) comprising:
An injector body (12) having a front end (16), a fuel inlet passage (30), a back leak passage (22), and a rear end (20) terminating at an end face (26);
For receiving fuel from the back leak passage (22) between the rear end (20) of the injector main body (12) by fitting to the rear end (20) of the injector main body (12). A cap (14) forming a chamber (60);
A seal (42) for sealing the chamber (60) to prevent fuel from flowing out of the chamber (60);
The fuel injector assembly, wherein the seal (42) is disposed between the end face (26) of the rear end (20) and the inlet end (32) of the fuel inlet passage (30). The fuel injector assembly according to claim 1, wherein
The fuel injector assembly, wherein the seal (42) comprises an O-ring. The fuel injector assembly according to claim 2, wherein
The cap (14) comprises a substantially cylindrical body (38);
The cylindrical body (38) is a fuel injector assembly in which a groove for seating the O-ring is formed on an inner surface thereof. The fuel injector assembly according to claim 2 or 3,
The fuel injector assembly, wherein the injector body (12) includes a groove for the O-ring to be seated. In the fuel injector assembly according to any one of claims 1 to 4,
An inlet end (32) of the fuel inlet passage (30) is formed on a side wall of the injector body (12),
The cap (14) includes an opening, and in use, fuel is passed through the opening and supplied to the fuel inlet passage (30). The fuel injector assembly according to claim 5, wherein
An inlet connector (36) having a fuel delivery passage (46);
The inlet connector can be secured to the cap (14) to extend through the opening, and fuel can travel from the fuel delivery passage (46) into the fuel inlet passage (30). Assembly. The fuel injector assembly according to any one of claims 1 to 6,
The fuel injector assembly, wherein the cap (14) includes an outlet (62) that is connectable to a back leak return line and is in flow communication with the chamber (60).   An internal combustion engine equipped with the fuel injector assembly according to any one of claims 1 to 7. The internal combustion engine according to claim 8,
The engine is equipped with a cover (70),
The internal combustion engine, wherein the rear end (20) and the cap (14) of the injector body (12) are arranged outside the cover (70).

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